A nonneuronal 5-hydroxytryptamine receptor 3 induces chloride secretion in the rat distal colonic mucosa |
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Authors: | Day Jarrod King Brian Haque Sheikh M Kellum John M |
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Affiliation: | Department of Surgery, Virginia Commonwealth Medical Center, West Hospital, 15th Floor, West Wing, 1200 Broad St., P.O. Box 980519, Richmond, VA 23298-0519, USA. |
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Abstract: | BACKGROUND: The 5-HT3 receptor is a serotonin receptor believed to reside on enteric neurons. However, several studies belie an exclusive neural localization. Our hypothesis is that the 5-HT3 receptor agonist, 2-methyl-5-HT (2Me5HT), induces chloride secretion despite neural blockade, which can be blocked by a 5-HT3 receptor antagonist. METHODS: Rat distal colon was stripped of its muscularis, mounted as mucosal sheets in Ussing chambers, and short-circuited. Adjacent sheets were pretreated with 1 micromol/L of the neurotoxin, tetrodotoxin, and incubated with 2Me5HT (50 micromol/L) alone or with a 5-HT3 (0.3 micromol/L ondansetron or 0.3 micromol/L tropisetron) or a 5-HT4 (0.3 micromol/L GR11808) receptor antagonist. Short-circuit current (I(sc)) was measured continuously. RESULTS: 2Me5HT caused an increase in I(sc), which was significantly (P <.01, repeated measures analysis of variance) inhibited by ondansetron (n = 8) and tropisetron (n = 5) but not by GR11808. CONCLUSIONS: A 5-HT3 receptor is present at the mucosal level that mediates chloride secretion by a nonneural pathway. |
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Keywords: | 5-hydroxytryptamine receptor 3 Intestinal secretion Serotonin |
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